Japan to go fishing...for space debris

An image created by Australia's Electro Optic Systems (EOS) aerospace company shows a view of the Earth from geostationary height depicting swarms of space debris -- approximately 50,000 of the half-million or more debris objects greater than 1cm -- in Low Earth Orbit (LEO).

Japan's space agency is reportedly teaming up with a fishing net manufacturer to catch and remove debris from Earth orbit, where it poses a threat to spacecraft, astronauts and satellites.

The space fishing net would span several kilometers and be made of thin metal wires. As it scoops up space debris, it will be charged with electricity, allowing Earth's magnetic field to reel in the haul and eventually burn it up in Earth's atmosphere, The Telegraph reports.

"You've got a charged object moving in a magnetic field. By the laws of physics, you are going to have a force, which is going to change its orbit," Brian Weeden, a former U.S. Air Force orbital analyst who is now a technical advisor for the Secure World Foundation, explained to me today.

Though Weeden is not familiar with the specifics of the Japan Aerospace Exploration Agency's fishing net plan, the space debris expert said the concept fits in with a class of ideas under consideration to remove junk from space.

A key innovation of the JAXA concept, he noted, is that it "solves the fuel problem. You don't have to carry fuel onboard; you just have to have a way of generating electricity, which you can do at those altitudes with solar panels."

The Secure World Foundation's Space Security 2010 report made space debris a top concern. Currently, the U.S. military is tracking 21,000 known objects bigger than 10 centimeters in Earth orbit. Of those, only about 1,000 are working satellites. The rest are dead satellites, rocket parts and other pieces of junk.

This space junk is large enough to destroy whatever it hits, according to Weeden. Another 300,000 or so pieces between one and ten centimeters wide are known to exist, but aren't routinely tracked. Most of this stuff, big and small, is in orbit with functioning satellites and other spacecraft.

"It's where the activity is because it’s a result of all the activity. That's really the problem," Weeden said. The fishing net concept and other ideas are the first concerted efforts at removing this hazardous junk.

Removing space debrisTo get the stuff, scientists and engineers need to figure out how to actually catch it. These pieces could be spinning out of control, and may be vulnerable to disintegration with a mere touch, due to years of radiation exposure. Some potentially could be filled with unused rocket fuel that could cause an explosion.

This makes grabbing it with a mechanical arm, for example, difficult if not impossible. "Let's say the piece of debris is spinning. Well then you've got to first de-spin it, otherwise it is just going to rip the arm right off," Weeden said.

The space fishing net that JAXA is developing with Nitto Seimo Co is one way to solve the problem of catching the debris, he added. Other concepts include spacecraft that attach themselves to debris and then de-orbit it into Earth's atmosphere with the aid, for example, of a solar sail.

Funding and legal questionsMost of the concepts, at this point, are early in the planning stage, noted Weeden. Nothing has yet been flown and flight tested. "The other big question is who pays for it," he said. "The economic question is a big issue and it is tied into some of the legal and policy questions."

For one, whoever launched the satellite owns it. It's essentially sovereign territory. So if, for example, a French cleanup mission scoops up a Russian-made piece of debris, there's a legal question concerning breach of national sovereignty.

Legal issues aside, policy experts are floating some ideas on paying the clean-up bill. One under consideration is an account along the lines of the Superfund, which is used to clean-up hazardous waste sites in the U.S. Another is a deposit program similar to that used in some states when consumers pick up a six-pack of soda or beer.

"You put your ten-cent deposit down — though it will likely be a lot bigger than that — when you launch the satellite, and you get it back when it is no longer in orbit," Weeden said.

Whatever technology is eventually used — and whoever ends up paying for it — clean-up needs to start by 2020 to "have a fairly significant impact in terms of making things safer in orbit," he added.